/****************************************************************************
 *
 * Copyright 2016 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * libc/stdio/lib_fopen.c
 *
 *   Copyright (C) 2007-2012 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <tinyara/config.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

#include "lib_internal.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/* Open mode flags */

#define MODE_R    (1 << 0)		/* Bit 0: "r{b|x|+}" open for reading */
#define MODE_W    (1 << 1)		/* Bit 1: "w{b|x|+}" open for writing, truncating,
								 * or creating file */
#define MODE_A    (1 << 2)		/* Bit 2: "a{b|x|+}" open for writing, appending
								 * the to file */
#define MODE_PLUS (1 << 3)		/* Bit 3: "{r|w|a|b|x}+" open for update (reading
								 * and writing) */
#define MODE_B    (1 << 4)		/* Bit 4: "{r|w|a|x|+}b" Binary mode */
#define MODE_X    (1 << 5)		/* Bit 5: "{r|w|a|b|+}x" Open exclusive mode */

#define MODE_NONE 0				/* No access mode determined */
#define MODE_MASK (MODE_R | MODE_W | MODE_A)

/****************************************************************************
 * Private Types
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: lib_mode2oflags
 ****************************************************************************/

int lib_mode2oflags(FAR const char *mode)
{
	unsigned int state;
	int oflags;

	/* Verify that a mode string was provided.  */

	DEBUGASSERT(mode);

	if (!mode || !*mode) {
		goto errout;
	}

	/* Parse the mode string to determine the corresponding open flags */

	state = MODE_NONE;
	oflags = 0;

	for (; *mode; mode++) {
		switch (*mode) {
		/* Open for read access ("r{b|x|+}") */

		case 'r':
			if (state == MODE_NONE) {
				/* Open for read access */

				oflags = O_RDOK;
				state = MODE_R;
			} else {
				goto errout;
			}
			break;

		/* Open for write access ("w{b|x|+}") */

		case 'w':
			if (state == MODE_NONE) {
				/* Open for write access, truncating any existing file */

				oflags = (O_WROK | O_CREAT | O_TRUNC);
				state = MODE_W;
			} else {
				goto errout;
			}
			break;

		/* Open for write/append access ("a{b|x|+}") */

		case 'a':
			if (state == MODE_NONE) {
				/* Write to the end of the file */

				oflags = O_WROK | O_CREAT | O_APPEND;
				state = MODE_A;
			} else {
				goto errout;
			}
			break;

		/* Open for update access ("{r|w|a|b|x}+") */

		case '+':
			switch (state & MODE_MASK) {
			case MODE_R: {
				/* Retain any binary and exclusive mode selections */

				oflags &= (O_BINARY | O_EXCL);

				/* Open for read/write access */

				oflags |= O_RDWR;
				state |= MODE_PLUS;
			}
			break;

			case MODE_W: {
				/* Retain any binary and exclusive mode selections */

				oflags &= (O_BINARY | O_EXCL);

				/* Open for write read/access, truncating any existing file */

				oflags |= (O_RDWR | O_CREAT | O_TRUNC);
				state |= MODE_PLUS;
			}
			break;

			case MODE_A: {
				/* Retain any binary and exclusive mode selections */

				oflags &= (O_BINARY | O_EXCL);

				/* Read from the beginning of the file; write to the end */

				oflags |= (O_RDWR | O_CREAT | O_APPEND);
				state |= MODE_PLUS;
			}
			break;

			default:
				goto errout;
				break;
			}
			break;

		/* Open for binary access ("{r|w|a|x|+}b") */

		case 'b':
			if ((state & MODE_MASK) != MODE_NONE) {
				/* The file is opened in binary mode */

				oflags |= O_BINARY;
				state |= MODE_B;
			} else {
				goto errout;
			}
			break;

		/* Open for exclusive access ("{r|w|a|b|+}x") */

		case 'x':
			if ((state & MODE_MASK) != MODE_NONE) {
				/* The file is opened in exclusive mode */

				oflags |= O_EXCL;
				state |= MODE_X;
			} else {
				goto errout;
			}
			break;

		/* Unrecognized or unsupported mode */

		default:
			goto errout;
			break;
		}
	}

	return oflags;

	/* Both fopen and fdopen should fail with errno == EINVAL if the mode
	 * string is invalid.
	 */

errout:
	set_errno(EINVAL);
	return ERROR;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: fdopen
 ****************************************************************************/

FAR FILE *fdopen(int fd, FAR const char *mode)
{
	FAR FILE *ret = NULL;
	int oflags;

	/* Map the open mode string to open flags */

	oflags = lib_mode2oflags(mode);
	if (oflags >= 0) {
		ret = fs_fdopen(fd, oflags, NULL);
	}

	return ret;
}

/****************************************************************************
 * Name: fopen
 ****************************************************************************/

FAR FILE *fopen(FAR const char *path, FAR const char *mode)
{
	FAR FILE *ret = NULL;
	int oflags;
	int fd;

	/* Map the open mode string to open flags */

	oflags = lib_mode2oflags(mode);
	if (oflags < 0) {
		return NULL;
	}

	/* Open the file */

	fd = open(path, oflags, 0666);

	/* If the open was successful, then fdopen() the fil using the file
	 * desciptor returned by open.  If open failed, then just return the
	 * NULL stream -- open() has already set the errno.
	 */

	if (fd >= 0) {
		ret = fs_fdopen(fd, oflags, NULL);
		if (!ret) {
			/* Don't forget to close the file descriptor if any other
			 * failures are reported by fdopen().
			 */

			(void)close(fd);
		}
	}
	return ret;
}
